<!DOCTYPE html>
<html lang="en">

<head>
    <meta charset="UTF-8" />
    <meta http-equiv="X-UA-Compatible" content="IE=edge" />
    <meta name="viewport" content="width=device-width, initial-scale=1.0" />
    <title>tab栏切换</title>
    <style>
        * {
            margin: 0;
            padding: 0;
        }

        .tab {
            width: 590px;
            height: 340px;
            margin: 20px;
            border: 1px solid #e4e4e4;
        }

        .tab-nav {
            width: 100%;
            height: 60px;
            line-height: 60px;
            display: flex;
            justify-content: space-between;
        }

        .tab-nav h3 {
            font-size: 24px;
            font-weight: normal;
            margin-left: 20px;
        }

        .tab-nav ul {
            list-style: none;
            display: flex;
            justify-content: flex-end;
        }

        .tab-nav ul li {
            margin: 0 20px;
            font-size: 14px;
        }

        .tab-nav ul li a {
            text-decoration: none;
            border-bottom: 2px solid transparent;
            color: #333;
        }

        .tab-nav ul li a.active {
            border-color: #e1251b;
            color: #e1251b;
        }

        .tab-content {
            padding: 0 16px;
        }

        .tab-content .item {
            display: none;
        }

        .tab-content .item.active {
            display: block;
        }
    </style>
</head>

<body>
    <div class="tab">
        <div class="tab-nav">
            <h3>每日特价</h3>
            <ul>
                <li><a class="active" href="javascript:;" data-id="1">精选</a></li>
                <li><a href="javascript:;" data-id="2">美食</a></li>
                <li><a href="javascript:;" data-id="3">百货</a></li>
                <li><a href="javascript:;" data-id="4">个护</a></li>
                <li><a href="javascript:;" data-id="5">预告</a></li>
            </ul>
        </div>
        <div class="tab-content">
            <div class="item active"><img src="./images/tab00.png" alt="" /></div>
            <div class="item"><img src="./images/tab01.png" alt="" /></div>
            <div class="item"><img src="./images/tab02.png" alt="" /></div>
            <div class="item"><img src="./images/tab03.png" alt="" /></div>
            <div class="item"><img src="./images/tab04.png" alt="" /></div>
        </div>
    </div>
    <script>
        const ul = document.querySelector('.tab-nav ul');
        // 一.导航栏切换业务
        ul.addEventListener('mouseover', function (e) {
            // 只有点到a时才会触发事件监听行为
            if (e.target.tagName === 'A') {
                // 排他原理
                document.querySelector('.tab-nav ul .active').classList.remove('active');
                e.target.classList.add('active');
                //二. 内容切换业务
                const i = +e.target.dataset.id;
                console.log(i);
                console.log(typeof (i));
                document.querySelector('.tab-content .active').classList.remove('active');
                document.querySelector(`.tab-content .item:nth-child(${i})`).classList.add('active')
            }
        }); 
    </script>
</body>

</html>